Huanglongbing, HLB, or citrus greening disease was first reported in southern China in 1919 (Reinkinget, al., 1919), but it has been suggested to have originated in Africa. The disease is now found in approximately 40 different Asian, African, North and South American countries and has recently become a serious threat in Florida, California, Louisiana, Texas and Brazil, all of which are major citrus producing locations. Citrus greening disease is caused by the phloem-limited fastidious prokaryotic α-proteobacterium Candidatus Liberibacter spp., Ca. africanus, and Ca. L. americanus. Two psyllids, Diaphorina citri Kuwayama and Trioza erytreaei, are known to vector the disease (Manjunath, et al., 2002). Citrus trees that become infected with the devastating citrus greening disease go into decline, producing mishappened, off-flavor fruit, and then die within a few years. The $1.4 billion annual Florida citrus industry (Ewing, et al., 2006-2007) is severely threatened by this vector-disease pathosystem. Further, the disease threatens to wipe out the $1.3 million annual citrus industry in California. Presently, there is no cure for this disease and trees are routinely destroyed once severely infected. Moreover, there are no known relevant cultivars that are resistant to citrus greening disease. Since 2005, it is estimated that about 650,000 trees have been destroyed in Brazil and a similar number in Florida to slow the disease.